Pivot bearing

ABSTRACT

A pivot bearing, e.g. for a vehicle trailing arm suspension, comprising a housing ( 4 ), a resilient bush ( 3 ), preferably compressed and bonded in the housing, and a rigid axial sleeve ( 2 ) in the bush, has voids, ( 9 ) formed in the bush to be above and below the sleeve when the pivot bearing is fitted for use, and there are stiffening elements ( 17 ) in the bush which extend between the voids ( 9 ) at opposite sides of the sleeve. When the pivot bearing is in use in a vehicle trailing arm suspension, the voids increase flexibility of the bush under generally vertical loading on the pivot bearing and the stiffening elements enhance the stiffness of the bush in generally horizontal direction for improved vehicle dynamics and reduced vibration. Preferably the siffening elements ( 17 ) are of plate or leaf form are bonded to the bush and extend arcuately about the sleeve, and the voids ( 9 ), which may extend partially through the axial thickness of the bush from opposite ends of the bush, extend generally accurately about the sleeve ( 2 ) and have enlarged opposite circumferential end portions ( 13 ). The end portions ( 13 ) extend circumferentially beyond diametrically opposite parts of the external circumference of the sleeve and are in-turned towards the sleeve. Edges ( 18 ) of the stiffening elements may extend into the opposite end portions ( 13 ) of the voids.

[0001] This invention relates to a pivot bearing, particularly, thoughnot exclusively, for a vehicle trailing arm suspension.

[0002] Pivot bearings in a vehicle trailing arm suspension are subjectedin use to forces in vertical, horizontal, axial and torsionaldirections. It is desirable that the bearings should be able to absorbthese forces, including shock and out of phase wheel loading, and have aprolonged useful life.

[0003] Conventionally, pivot bearings for vehicle trailing armsuspension systems comprise a housing containing a generally cylindricalbush on a rigid axial sleeve in which a pivot of a trailing arm islocated. Whilst being essentially stiff, the bush has some resilienceintended to absorb vertical, horizontal and torsional forces,particularly roll induced forces and out of phase wheel loads. Usuallythe bush is made of a rubber material. Bushes have been made solid andwith the same level of stiffness/resilience all around the axial sleeve.This limits the effectiveness of the bush because thestiffness/resilience requirements at different angularly positionedparts of the bush around the pivot may vary appreciably in practiceaccording to the direction in which loads are exerted on the bush inuse. If the bush is heavily loaded in use it will usually have a highlevel of stiffness which makes it too stiff for satisfactory absorptionof loads. Alternatively, if the bush is made with a compromise level ofstiffness/resilience for the range of loads exerted on it in use indifferent directions, its performance is clearly limited.

[0004] In order to vary the stiffness of the bush for different levelsof forces acting on the pivot bearing from different directions in use,bushes have been made with voids, usually arcuate, above and below theaxial sleeve. This softens the rate of the bush under general verticalloading whilst retaining greater stiffness in the generally longitudinaldirection of the vehicle for compliance under roll and out of phasewheel loading. However, the stiffness provided in the generallylongitudinal direction is limited and may be insufficient to copesatisfactorily with increasing loading conditions under which somevehicles are expected to operate.

[0005] According to a first aspect of the present invention a pivotbearing is provided, comprising a housing by which the pivot bearing isattached to support means for use, a resilient generally cylindricalbush contained in the housing, and a rigid axial sleeve secured in thebush at which the pivot bearing is located for use, the bush beingformed with voids in first portions thereof which when the pivot bearingis fitted for use are disposed above and below the axial sleeve, andhaving stiffening elements of stiffer material than that of the bushcontained in second portions of the bush extending between said firstportions at opposite sides of the axial sleeve.

[0006] The stiffening elements increase the stiffness of the bush ingenerally horizontal directions for improved vehicle dynamics andreduced vibration when the pivot bearing is in use.

[0007] The stiffening elements may be rigid. They may, for example, beof metal such as steel, or be of a suitable plastics material.Preferably the stiffening elements are securely retained, by bonding, tothe bush. They may be of a plate or leaf form. The elements may extendarcuately in the second portions about the sleeve. They may take otherforms. There may be a single stiffening element at each side of thesleeve, or there may be more than one. Each stiffening element mayextend through the axial length of the bush, and may project from theopposite ends of the bush.

[0008] The bush is preferably formed by moulding, the voids being formedin the bush as it is moulded. The stiffening elements may beincorporated into the bush as it is moulded; the material of the bushmay then be bonded to the elements in the course of the mouldingprocess.

[0009] The voids may extend arcuately, or generally arcuately, in thefirst portions of the bush about the sleeve. They may extend through theaxial thickness of the bush, or partially through the thickness. Voidsmay extend into the bush from opposite end faces of the bush. In thislatter arrangement similar, directly opposed, voids may extend towardsone another from the opposite end faces but be separated by a centralsolid region of the bush.

[0010] Preferably as viewed from each of the opposite ends of the bush,in the position of use of the pivot bearing, there is one elongated voidabove and one below the sleeve, each void extending for a longerdistance about the sleeve than the external diameter of the sleeve.Opposite ends of each void extend through and beyond notional parallelplanes extending vertically tangentially of diametrically opposite partsof the external circumference of the sleeve. This increases theflexibility of the bush under generally vertical loading. Preferably theends of the voids are also enlarged which assists in reducing stressesin the material of the bush at the ends of voids and facilitatescompression of the bush under vertical loading. Enlargement may beprovided by increasing the annular width of the end regions of thevoids. In another form the ends of the voids may be enlarged by shapingthem into two or more lobes, fingers or comparable projections runningfrom the main bodies of the voids. At least one such projection at eachend of a void may extend inwardly towards the sleeve. In a preferredform the enlargements are provided by having the ends of the voidsturned inwardly towards the sleeve. The ends may be turned inwardly atan angle, preferably substantially radially of the sleeve. Each end maytaper generally triangularly towards the sleeve.

[0011] The bush may be an interference fit in the housing.Alternatively, it may be bonded and/or moulded into the housing.

[0012] In a preferred embodiment the bush is formed, as by moulding,separately from the housing and is then compressed into and bonded inthe housing. The bush is fixed on the sleeve before its insertion intothe housing. The voids of the uncompressed bush are open so that theopposite longitudinal sides of the elongated voids extending above andbelow the sleeve are spaced apart. Ends of the voids are turned inwardlytowards the sleeve in the manner described above and taper generallytriangularly towards the sleeve. Upon insertion of the bush into thehousing, and its radial compression thereby, the compression of thefirst portions containing the voids causes the opposite longitudinalsides of the voids to close together. In the assembled pivot bearing,therefore, the voids are substantially closed; only the inturned ends ofthe voids may remain open, though to a lesser extent than in theuncompressed state of the bush. Although the voids are closed the firstportions remain relatively compressible, thereby affording substantialcompliance in the bush under loading in vertical, and generallyvertical, directions.

[0013] By contrast, the compression of the bush at the second portionsresulting from its insertion into the housing in combination with thestiffening afforded by the stiffening elements leaves the secondportions substantially stiffened against further compression underhorizontal, and generally horizontal, loading on the bush when it is inuse.

[0014] The stiffening elements, at least in the plate or leaf form, mayextend into opposite ends of the voids. When the ends of the voids areenlarged into lobes, fingers or comparable projections, as described,the stiffening elements preferably extend into the voids betweenadjacent projections. In the preferred form of the voids having theinwardly turned ends the material of the bush is radiused into the endsof the voids at the stiffening elements where the elements break intothe voids. These arrangements reinforce the bush where stresses areconcentrated under vertical, and generally vertical, loading and help toprevent separation of the material of the bush from the stiffeningelements adjacent the voids.

[0015] The bush may be bonded to the sleeve. When the bush is made as amoulding it may be bonded onto the sleeve as it is moulded. The sleevemay protrude from the opposite end faces of the bush.

[0016] The sleeve may be axially longer than the housing for complianceof the bush under axial and tilting loading. The sleeve may projectsymmetrically from the opposite axial ends of the housing. Preferablythe bush is shaped to correspond substantially in axial length to thelength of the sleeve at its internal diameter and to have its endsinclined away from the sleeve so that the axial length of the bushreduces towards its external diameter. This allows for tilting of thebush relative to the sleeve and bulging of the ends under loading.

[0017] In one embodiment, a pivot bearing is made to be used in avehicle trailing arm and its attachment to a supporting part of thevehicle. The pivot bearing is designed to withstand horizontal,vertical, axial and torsional loading when in use. The housing of thepivot bearing is cylindrical and co-axial with the sleeve. The bush isbonded onto the rigid axial sleeve and securely retained in the housing.Both the sleeve and housing are made of metal, for example steel. Thebush has a cylindrical body with frusto-conical, or convex, end faces.The sleeve is longer than the housing and projects from the end faces ofthe body. The body is made of a rubber, polyurethane, or comparable,flexible material. Generally arcuately extending elongated voids areformed in first portions of the body which when the pivot bearing isfitted for use are above and below the sleeve, the voids opening throughthe end faces of the body. The voids are longer arcuately than theexternal diameter of the sleeve and have inwardly turned end portionswhich taper triangularly, generally radially, towards the sleeve.Stiffening elements extend through the second portions of the bodyadjacent diametrically opposed sides of the sleeve. There is onestiffening element at each side of the sleeve. The stiffening elementsare made of metal, for example steel, and are of a plate or leaf formarcuately curved concentrically about the sleeve. They extend throughthe full axial length of the body and protrude from the opposite endfaces of the body but are shorter than the sleeve. Each stiffeningelement projects into the adjacent end portions of the voids.

[0018] The housing is fixed to the trailing arm for use of the pivotbearing such that the central longitudinal axis of the sleeve extendshorizontally transversely of the arm. A pivot pin is located in thesleeve and supported by opposed limbs of a mounting which straddles thepivot bearing and is fixed to the supporting part of the vehicle. Theprotruding ends of the sleeve abut, or bear on thrust washers whichabut, opposed inner surfaces of the respective limbs of the mounting. Inuse of the suspension system generally vertical and horizontal loadingsimposed on the pivot bearing by relative movement between the pivot pinand trailing arm are accommodated respectively by the voided firstportions of the bush and the second portions stiffened by the stiffeningelements. The body of the bush is able to sustain axial, torsional andtilting loading on the bush.

[0019] The pivot bearing may be included as original equipment on atrailing arm of a vehicle trailing arm suspension system.

[0020] Thus, according to a second aspect of the present invention thereis provided a vehicle trailing arm including a pivot bearing inaccordance with the first aspect of the invention herein set forth, thehousing of the pivot bearing being fixed with respect to the trailingarm.

[0021] According to a third aspect of the present invention there isprovided a vehicle trailing arm suspension system including at least onetrailing arm in accordance with the foregoing second aspect of theinvention.

[0022] An embodiment of the invention will now be described by way ofexample only with reference to the accompanying drawings, in which:

[0023]FIG. 1 is an end view of a bush of a pivot bearing in accordancewith the present invention,

[0024]FIG. 2 is an axial section through the bush on line 2-2 of FIG. 1,

[0025]FIG. 3 is an end view of the pivot bearing including the bush ofFIGS. 1 and 2,

[0026]FIGS. 4 and 5 are end views of the bush showing modifications,

[0027]FIG. 6 is a perspective view of a trailing arm suspension systemincluding the pivot bearing of FIG. 3.

[0028] The pivot bearing in this embodiment of the present invention isto be used in a vehicle trailing arm suspension system.

[0029] Referring to FIG. 3, the pivot bearing comprises a housing 1, anaxial sleeve 2 and a bush 3.

[0030] The housing 1 is cylindrical being made of circular section steeltube. The sleeve 2 is also made of circular section steel tube and islonger than the housing

[0031] The bush 3, as best seen in FIGS. 2 and 3, comprises acylindrical body 4 of a rubber material having a substantial degree ofstiffness but some resilience. The body is concentrically moulded onto,and bonded to, the sleeve 2. It is of an external diameter such that ithas to be radially compressed to fit into the housing 1 and of a lengthto be fully received at its outer cylindrical surface into the housing.Opposite end faces 5 are shallowly frusto-conical. They merge into theexternal cylindrical surface 6 of the body at convexly radiused edges 7and meet the external surface of the sleeve 2 at concave radii 8. Thesleeve projects symmetrically from the opposite end faces 5 of the body4.

[0032] Extending into the body 4 from each of the opposite end faces aretwo similar voids 9. The voids 9 are formed in the body as it ismoulded. They are in diametrically opposed segments of the body whichwhen the pivot bearing is fitted for use are respectively above andbelow the sleeve. The voids 9 at one end face are axially directlyopposite those of the other end face. The voids extend almost to, butare separated by a solid web 10 of the material of the body at, thecentre of the length of the body. They taper gradually towards theirclosed axially inner ends.

[0033] In the free state of the body as moulded, before the bush isinserted into the housing, as shown in FIG. 3, each void 9, as viewed atthe end faces 5 of the body, is elongated, having an arcuate outer sidewall 11 curved about, but having a radius of curvature greater than itsdistance from, the central longitudinal axis of the body, and an innerside wall 12 of a larger radius of curvature extending substantially asa chord of the arc of the outer side wall. The void is of substantiallygreater length than the external diameter of the sleeve 2. Its oppositeend portions 13 are enlarged by being turned generally radially inwardlyin similar manner. Each end portion is of a substantially isoscelestriangle shape elongated towards the sleeve, one side 14 extending fromthe inner side wall 12 of the void and the opposite side 15 extendingfrom the outer side wall 11, and being directed generally towards thecentral longitudinal axis of the body. The portion of the body betweeneach void 9 and the sleeve 2 forms a buffer 16 of the bush.

[0034] Set in the body 4 of the bush as it is moulded are two similarrigid metal stiffening elements 17. The stiffening elements are securelybonded to the material of the body. They are in two diametricallyopposed segments of the body between the two segments containing thevoids 9. Each stiffening element 17 is in the form of a generallyrectangular leaf which is bowed co-axially about the centrallongitudinal axis of the body. The two stiffening elements are similarlyradially spaced from the sleeve. They extend through the full axiallength of the body and protrude from the end faces 5 of the body, but donot extend as far as the ends of the sleeve. Opposite side edges 18 ofthe stiffening elements, at the extremities of the bows of the elements,extend through the sides 15 of the adjacent end portions 13 of thevoids, substantially opposite the inner side walls 12, and project intothe voids. Side walls 15 are concavely radiused to merge with the sideedges 18 of the stiffening elements so as to enhance resistance toseparation of the material of the bush from the extremities of the bowsof the stiffening elements. The portions of the segments of the bodyradially inside and outside of the stiffening elements 17 form shearblocks 19 of the bush.

[0035] As stated, the body is radially compressed to fit into thehousing. The compression of the body results in the outer and inner sidewalls 11, 12 of the voids 9 being urged together so that the voids areeffectively closed between those walls, as shown in FIG. 1. The opposedsides 14, 15 of the end portions 13 of the voids are also urged towardsone another but though the end portions are narrowed they are notclosed.

[0036] The stiffening elements 17 substantially increase the stiffnessof the body of the bush in horizontal, and generally horizontal,directions, i.e. at the shear blocks 19, for fore and aft loading on thebush when the pivot bearing is in use. They considerably reduce theextent of the deflection of the body under such loading. It has beenfound that the extent of the deflection may be reduced to up to as muchas half that which may be experienced in a bush without the stiffeningelements but otherwise similar. The increased stiffness, which increasesnon-linearly with increasing loading, is particularly advantageous whenthe pivot bearing is used in a trailing arm suspension for a trailervehicle because of the improved stability it provides for the vehiclewhen carrying high loads with a high centre of gravity. The stiffnessalso reduces self-induced steering effects in the pivot bearing, reducestyre wear in the vehicle and generally helps to enhance the durabilityof the vehicle's running gear in use.

[0037] On the other hand, the provision of the voids 9 in the body,though closed when the bush is compressed into the housing, affordsappreciable resilience in the segments of the body in which they areformed, including the buffers 16, thereby giving the bush substantialresilience under the loading in vertical, and generally vertical,directions.

[0038] Resilience in the body allows relative axial and tilting movementbetween the bush and sleeve under loading in the generally axialdirection of the pivot bearing.

[0039] Compliance in roll and out of phase wheel loading manoeuvres ofthe vehicle to which the pivot bearing is applied in use is improved bythe differing degrees of deflection provided for in the bush.

[0040] Two modified forms of the voids 9 in the body of the bush areshown in FIGS. 4 and 5 of the drawings.

[0041] Referring to FIG. 4, each void 9 is elongated, having an arcuateouter side wall 20 curved about the central longitudinal axis of thebody and substantially straight inner side wall 21 extending along achord of the arc of the outer side wall. Under generally verticalloading on the body the outer and inner side walls 20, 21 will be urgedtowards one another and the inner side wall will assume a curvaturewhich increases towards that of the outer side wall with increasingloading. The void is of substantially greater length that the externaldiameter of the sleeve 2. Its opposite end portions 22 are enlarged insimilar manner, each end portion being shaped into two divergent lobes23, 24 with one, inner, lobe 23 being directed generally toward thecentral longitudinal axis of the body. A cuspidated land 25 separatesthe two lobes 23, 24.

[0042] In this form of the voids 9 the opposite side edges 18 of thestiffening elements 17 extend through the lands 25 at the adjacentenlarged end portions 22 of the voids and project into the voids. Thearrangement resists separation of the material of the bush from theextremities of the bows of the stiffening elements.

[0043] Referring now to FIG. 5, in this form the voids 9 are elongatedto a similar extent as before, but an inner side wall 25 of each void isarcuately curved co-axially about the sleeve 2 and a central portion 27of an outer side wall 28 is oppositely, inwardly, curved, although witha similar radius of curvature. Thus the two side walls 26, 28 areconvergent at the central part of the void. At either side of theinwardly curved central portion 27 the curvature of the outer side wall28 reverses so that the end portions 29 of the wall curve co-axiallyabout the sleeve 2, parallel to the inner side wall. There is a smoothradiused transition between the central and end portions of the outerside wall 28. The change of curvature of the outer side wall results inopposite end portions 30 of the void being enlarged. A substantial partof the enlargement of the end portions 30 is beyond the saidhorizontally diametrically opposed sides of the external circumferenceof the sleeve. Each end wall 31 of each void is cuspidated on thecentral longitudinal axis of the void.

[0044] The opposite side edges 18 of the stiffening elements 17 projectinto the voids 9 at the centres of their cuspidated end walls 31.

[0045] An example is shown in FIG. 6 of the drawings of a trailing arm32 of a vehicle trailing arm suspension system in which the pivotbearing described with reference to FIGS. 1 to 3 may be included. Thissystem is suitable for a heavy trailer vehicle. The arm 32 is fabricatedfrom metal plate. The pivot bearing, indicated at 33, is securedtransversely in one bifurcated end 34 of the arm 32. At its opposite endthe arm is provided with a seat 35 for an air spring, not shown, and atan intermediate part of its length the arm has an axle 36 attached to itby means of a wrapper 37.

1. A pivot bearing comprising a housing (1) by which the pivot bearingis attached to a support means for use, a resilient generallycylindrical bush (3) contained in the housing, and a rigid axial sleeve(2) secured in the bush at which the pivot bearing is located for use,characterised in that the bush is formed with voids (9) in firstportions thereof which when the pivot bearing is fitted for use aredisposed above and below the axial sleeve (2), and has stiffeningelements (17) of stiffer material than that of the bush contained insecond portions of the bush extending between said first portions atopposite sides of the axial sleeve (2).
 2. A pivot bearing according toclaim 1 characterised in that the stiffening elements(17) are rigid. 3.A pivot bearing according to claim 2 characterised in that thestiffening elements (17) are made of metal.
 4. A pivot bearing accordingto claim 2 characterised in that the stiffening elements (17) are madeof a plastics material.
 5. A pivot bearing according to any precedingclaim characterised in that the stiffening elements (17) are securelyretained to the bush (3).
 6. A pivot bearing according to claim 5characterised in that the stiffening elements (17) are bonded to thebush (3).
 7. A pivot bearing according to any preceding claimcharacterised in that the stiffening elements (17) are of plate or leafform.
 8. A pivot bearing according to any preceding claim characterisedin that the stiffening elements (17) extend arcuately in the secondportions about the sleeve (2).
 9. A pivot bearing according to anypreceding claim characterised in that there is a single one of thestiffening elements (17) at each of said second portions.
 10. A pivotbearing according to any of claims 1 to 8 characterised in that there ismore than one of the stiffening elements at each of said secondportions.
 11. A pivot bearing according to any preceding claimcharacterised in that each stiffening element (17) extends through theaxial length of the bush (3).
 12. A pivot bearing according to claim 11characterised in that each stiffening element (17) projects from theopposite ends (5) of the bush (3).
 13. A pivot bearing according to anypreceding claim characterised in that the bush (3) is formed bymoulding, the voids (9) being formed in the bush (3) as it is moulded.14. A pivot bearing according to claim 13 characterised in that thestiffening elements (17) are incorporated into the bush (3) as it ismoulded.
 15. A pivot bearing according to claim 14 as dependent fromclaim 6 characterised in that the stiffening elements (17) are bonded tothe material of the bush (3) in the process of moulding the bush.
 16. Apivot bearing according to any preceding claim characterised in that thevoids (9) extend at least generally arcuately in the first portions ofthe bush(3) about the sleeve (2).
 17. A pivot bearing according to anypreceding claim characterised in that the voids (9) extend through theaxial thickness of the bush (3).
 18. A pivot bearing according to any ofclaims 1 to 16 characterised in that the voids (9) extend partiallythrough the axial thickness of the bush (3).
 19. A pivot bearingaccording to claim 18 characterised in that the voids (9) extend intothe bush (3) from axially opposite end faces (5) of the bush.
 20. Apivot bearing according to claim 19 characterised in that the voids (9)comprise similar, directly opposed, voids which extend towards oneanother from the opposite end faces (5) of the bush (3) and areseparated by a central solid region (10) of the bush.
 21. A pivotbearing according to any preceding claim characterised in that, asviewed from each of axially opposed end faces (5) of the bush (3), inthe position of use of the pivot bearing, there is one of the voids (9)above and below the sleeve (2), each void (9) being elongated withrespect to the circumference of the sleeve and extending for a longerdistance about the sleeve than the external diameter of the sleeve. 22.A pivot bearing according to claim 21 characterised in that, as viewedin the position of use of the pivot bearing, opposite circumferentialends (13;22;29) of each void (9) extend through and beyond notionalparallel planes extending vertically tangentially of diametricallyopposite parts of the external circumference of the sleeve (2).
 23. Apivot bearing according to claim 21 or claim 22 characterised in thatthe circumferential ends(13;22;29) of the voids (9) are enlarged wherebystresses in the material of the bush at the ends of the voids arereduced and compression of the bush under vertical loading on the pivotbearing when in use is facilitated.
 24. A pivot bearing according toclaim 23 characterised in that the ends (29) of the voids (9) areenlarged by increasing the annular width of the end regions of thevoids.
 25. A pivot bearing according to claim 23 characterised in thatthe ends (22) of the voids (9) are enlarged by shaping them into two ormore lobes (23,24), fingers or comparable projections running from themain bodies of the voids.
 26. A pivot bearing according to claim 25characterised in that at least one of the projections (23) at each end(22) of each void (9) extends inwardly towards the sleeve(2).
 27. Apivot bearing according to any of claims 24 to 26 characterised in thatthe ends (13) of the voids (9) are turned inwardly towards the sleeve(2).
 28. A pivot bearing according to claim 27 characterised in thatends (13) of the voids (9) are turned inwardly at an angle.
 29. A pivotbearing according to claim 28 characterised in that the ends (13) of thevoids (9) are turned inwardly substantially radially of the sleeve (2).30. A pivot bearing according to any of claims 27 to 29 characterised inthat the ends (13) of the voids (9) each taper generally triangularlytowards the sleeve (2).
 31. A pivot bearing according to any of claims21 to 30 characterised in that the stiffening elements (17) extend intothe opposite ends (13,22,29) of the voids (9).
 32. A pivot bearingaccording to claim 31 as dependent from any of claims 26 to 30characterised in that the material of the bush (3) is radiused into theends of the voids (9) at the stiffening elements (17) where thestiffening elements break into the voids.
 33. A pivot bearing accordingto claim 25 and either of claims 31 and 32 characterised in that thestiffening elements(17) extend into the ends of the voids(9) betweenadjacent projections (23,24) of the ends (22).
 34. A pivot bearingaccording to any preceding characterised in that the bush (3) is bondedto the sleeve (2).
 35. A pivot bearing according to claim 34 asdependent from claim 13 characterised in that the bush (3) is bondedonto the sleeve (2) as the bush is moulded.
 36. A pivot bearingaccording to any preceding claim characterised in that the sleeve (2)protrudes from opposite ends (5) of the bush (3).
 37. A pivot bearingaccording to any preceding claim characterised in that the bush (3) isshaped to correspond at its internal diameter substantially in axiallength to the length of the sleeve (2) and to have its ends (5) inclinedaway from the sleeve so that the axial length of the bush reducestowards its external diameter.
 38. A pivot bearing according to anypreceding claim characterised in that the bush (3) is an interferencefit in the housing (1).
 39. A pivot bearing according to any of claims 1to 38 characterised in that the bush (3) is bonded and/or moulded intothe housing (1).
 40. A pivot bearing according to claim 38 as dependentfrom claim 16 or from any of claims 21 to 33 characterised in that thebush (3) is compressed into and bonded in the housing (1), and the voids(9) of the compressed bush are substantially closed.
 41. A pivot bearingaccording to claim 40 as dependent from any of claims 26 to 30 or 32 orfrom claim 33 when dependent from claim 32, characterised in that thein-turned ends (13) of the voids (9) of the compressed bush (3) areopen.
 42. A vehicle trailing arm (32) characterised in that it includesa pivot bearing (33) as claimed in any preceding claim, the housing (1)of the pivot bearing being fixed with respect to the trailing arm.
 43. Avehicle trailing arm (32) according to claim 42 characterised in thatthe pivot bearing (33) is in accordance with claim 36 or claim 37 and apivot pin is located in the sleeve (2) and supported by opposed limbs ofa mounting which straddles the pivot bearing and fixes to a supportingpart of the vehicle for use of the trailing arm, the ends of the sleeveabuting, or bearing on thrust washers which abut, opposed inner surfacesof the respective limbs of the mounting.